add persistent custom centmin.sh options file support at inc/custom_config.inc
supports 2 locations for custom_config.inc
1). inc/custom_config.inc where centmin.sh base directory resides
2). at ${CONFIGSCANBASE}/custom_config.inc which defaults to /etc/centminmod/custom_config.inc
to override centmin.sh settings and allow them to persist on centmin mod code updates, create a
custom_config.inc at one of the 2 locations mentioned above and add the centmin.sh option to the
custom_config.inc file i.e.